Circuit cutout



Nov. 11, 1941. 5. SHAW 2,262,344 011101111 cu'rou'r Filed man 5, 1940 Patented Nov. 11, 1941 CIRCUIT CUTOUT Burton E. Shaw, Bristol Electric Switch (30., tion oi Iowa Ind, assignor to Penn Goshen, Ind., a corpora- Application March 5, 1940, Serial No. 322,286

Claims.

The circuit cut-out contemplated in the present application is particularly designed for breaking a circuit when the current therethrough exceeds a predetermined amount and recloses the circuit after a predetermined time period, the cut-out again operating in its cut-out capacity it the circuit still remains in an overloaded condition.

One object of the invention is to provide a circuit cut-out which includes a thermal relay and a magnetic relay so associated that a predetermined timing period can be secured without having to compensate the heat responsive element for ambient temperature.

A further object is to provide a magnetic relay which attracts an armature when current in excess of a predetermined amount flows through the relay coil and the armature then eflects the establishment of a circuit through a heating element, whereupon the heating element heats a heat responsive element such as one made of bimetal and warps it to a position where it opens the circuit to both the magnetic relay and the thermal relay, thereby breaking the circuit supplied to the cut-out.

A further object is to provide for re-establishment of the circuit through the cut-out only after a time period has expired, such time period being determined by the return warping oi the bimetal element as it cools down from its heated condition toward atmospheric temperature, the bimetal element eventually re-establishing the circuit through the cut-out and thereby the circuit through the magnetic relay, whereupon it the overloaded condition is still present the cutout recycles.

More particularly, it is my object to provide a cut-out including a magnetic relay and a ther-" mal relay having circut connections which are normally in a position to shunt out the thermal relay and efiect energization of the thermal relay only when current in excess of a predetermined amount flows through the magnetic relay coil,

an armature of the-magnetic relay being thereby attracted and operating to establish a circuit through the thermal relay so that it in turn can ,operate to connect the heating element of. the

thermal relay in series with the coil of the magnetic relayand thereby break the circuitthrough the cut-out, by operation 01' the thermal relay.

Although the invention is susceptible of a variety-of embodiments, it is unnecessary to fully describe and illustrate more than one in order to give a full understanding of the invention both from its structural and functional standpoints. Accordingly, I have illustrated a preferred and desirable embodiment of the invention in the accompanying drawing forming a part of this specification and throughout the views of which like reference characters refer to the same parts.

In the drawing:

Figure 1 is a side elevation of a circuit cut-out embodying my invention:

Figure 2 is an end elevation thereof;

Figure 3 is a sectional view on the line 3-3 of Figure 1 showing a plan view of the circuit cut-out with the exception of the armature, which is shown in dash lines;

Figure 4 is a vertical sectional view on the line 4-4 of Figure 1;

Figure 5 is a vertical sectional view on the line 5-5 of Figure 1;

Figure 6 is an electrodiagrammatic view showing the parts 0! the circuit cut-out in an intermediate position, and

Figure 7 is a similar view showing the parts in another intermediate position.

On the accompanying drawing, I have used the reference numeral I. to indicate generally a panel or other support, on which my cut-out is mounted. The cut-out itself includes a core member C having a center leg i2 and a pair of end legs I! and il. Wound on the center leg I2 is a magnetic coil Ii, insulation Ii being provided to insulate the coil from the core.

A base I 1 of insulating material is mounted on the core member C by means of a pair of lugs II at one end of the base, being received in notches I! 01' the core leg I 3. The other end of the base I1 is held in position by pairs of lugs 2| formed on the leg I4 and bent to overlap two of the corners'oi' the base l1.

An armature 2| is pivotally mounted on the core leg I by means or notches 22 in the armature receiving projections 22 of the leg H. A

leaf spring 24 of L shape has one flange secured to the armature 2| as by rivets 2|, and its other flange secured to the core leg M-"as by a screw 26. The spring 24 is so shaped initially that it tends to hold the armature 2| in the elevated position shown in Figure 1, with the side of the notches 22 engaging the extensions 23 to serve as a stop. The end of the armature opposite the pivoted end is adapted to be attracted by the core leg it when it is sumc'iently magnetized. A non-magnetic rivet 21 is provided in the armatureI 2| to prevent it from sticking to the core leg I.

Mounted on. the base ll 22. The spring 20, secured to the base isacontactspring asshowninFigure3,is

by arivet 2'. The spring 7!.

A bracket 38 is mounted on the base II by I means of a screw 39. The bracket 38 carries a third contact 48. A wire 4| connects the bracket 38 electrically with one end of the coil I5, 2. current supply wire 42 being connected with the other end thereof. A current supply wire 43 is soldered into a connector lug 44 and the lug in turn is connected to the rivet 34, so that current is supplied to the bimetal element 35. An enlarged opening 44 is provided for the lug 44 to pass through the core member C.

A heating element 45 is connected at one end to the contact rivet 48 and at its other end to the yoke of the leaf spring 28 by a rivet 46. The circuit connections resulting from the fore-' going described arrangement are shown in Figures 6 and 7.

Practical operation In the operation of my circuit cut-out, as long as the current supplied to the wires 42 and 43 is below a predetermined amount, the coil l5 energizes the core C insufficiently to attract the armature 2|. The circuit connections may be traced in Figure 6 as follows: From the wire 43 through the bimetal element and the contacts 31, 40, the wire 4| and the coil |5 back to the wire 42. Normally, the armature is elevated to the dotted position of Figure 6 so that the first and fourth contacts 33 and 36 are separated from each other, as shown in Figure 5.

When the current flowing through the cut-out exceeds a predetermined value, determined by the size of the coil l5, the spacing of the armature 2| from the core leg l3, etc., the armature is attracted, first assuming the intermediate position shown by full lines in Figure 6. All of the contacts are now engaged with each other, but there is no change in operation from the position asillustrated in Figure 5. As soon as the armature 2| starts to move, however, it moves all the way, because it is immediately in' a stronger magnetic field and therefore will move to the position of Figure '7. In this position, the second contact 31 has been separated from the third contact by the insulating button 2|- of the armature 2| having pressed the fourth contact into engagement with the first contact 36, as

shown in Figure 6, and then depressed the bimetal element 35 as shown in Figure 7 by solid lines.

The circuit connections through the cut-out are now change to the extent that the circuit is also flowing through the heating element 45. This raises the temperature of the heating element and the heat is radiated to the bimetal elementso that it warps to the dotted line position and thereby opens the circuit across the first and fourth contacts 36 and 33. The circuit is now'completely opened through the cut-out and the armature returns due to the spring 24 to its initial position shown in Figure 5, which position is indicated by dotted lines in Figure 'I. It will now take some time for the heating element to cool down sufllciently to re-establish the circult across the contacts 33 and 36, which gives a timing period during which the overload condition might be removed from the line. If so, the armature 2| will not be reattracted, whereas if the overload condition still prevails, such attraction will occur and the cut-out will re-cycle.

The magnetic relay of my cut-out determines the point at which cut-out operation occurs. Whenever the current is sufficient to cause attraction of the armature, then the thermal relay is thrown into operation. The thermal relay is designed so that it operates promptly and radiates enough heat to the bimetal element 35 so that it will remain warped out for a substantial period of time. This period may vary anywhere from several seconds to a few minutes, if desired.

Due to my arrangement, wherein the timing period is determined by the rate of return of the bimetal element 35, it is unnecessary to provide for ambient temperature compensation, ,as in many types of thermal relays. My cut-out is particularly adaptable for automobile radio installations. Automobile radios usually include a vibrator, with which trouble is experienced sometimes, especially in the winter-time, as the vibrator contacts sometimes stick together and thereby throw a dangerously high overload on the circuit. This overload, although usually insufficient to immediately blow a fuse, will do so after a period of time because of the prolonged flow of current through the fuse. Thereby much trouble has been experienced in blowing fuses with automobile radios.

Vibrators of the type mentioned usually become operative after the car is warmed up somewhat from driving it, and therefore a re-cycling cut-out of the kind I have described is a convenience as a means to avoid blowing out of the fuse. Sometimes after one or two recycling operations, the vibrator will operate satisfactory,

whereas if the. contacts of the vibrator are so' turns on his radio, and that the recycling does not stop, then it is an indication that the condition of the vibrator should be examined.

I have illustrated and described my improvement in an embodiment which I have found very satisfactory. I have not attempted to illustrate or describe certain adaptations or modifications which I contemplate, or the various uses and adjustments possible, as it is believed that the foregoing disclosure will enable those skilled in the art to which this invention appertains to embody; or adapt my improvements as may be desire Having thus described my invention, I now claim and desire to secure by Letters Patent:

1. A circuit cut-out of the character described comprising a relay including a coil and an armature. said armature being moved from normal position only when current through said coil exce'eds a predetermined amount, a heating ele-- 2,262,344 opening said other switch and maintaining the circuit open until said bimetal element cools sufllciently to return to closed circuit position of said first switch.

2. A circuit cut-out for a pair ofcircuit connections comprising a magnetic relay and a thermal relay including a heating element, one of said circuit connections being with one end of the coil of said magnetic relay, and said coil, the

heating element of said thermal relay and the temperature responsive element of said thermal relay being connected in series, the other of said circuit connections being with said temperature responsive element which normally makes contact with the circuit between said heating element and said coil, said temperature responsive element being movable by the armature of said magnetic relay upon energization of the coil of said magnetic relay by current in excess of a predetermined amount to break said contact with the circuit between said heating element and said coil and thereby eilect said series connection of said coil, said heating element and said temperature responsive element, said temperature responsive element thereupon breaking contact in the circuit through said cut-out at a point between said heating element and said temperature responsive element and returning to circuit restoring position after a time period de'- termined by dissipation of heat from said temperature responsive element to atmosphere.

3. A cut-out for a circuit having two wires comprising a magnetic relay and a thermal re"-- lay including a heating element, the coil of said magnetic relay having one end connected to one wire of the circuit and the coil and the heating element of said thermal relay being connected in series, the temperature responsive element of said thermal relay including a pair of contacts, one of which normally shunts said heating element out of the circuit by contact with a point thereof intermediate said coil and said heating element and being movable by the armature of said magnetic relay upon energization of the coil of the relay by current in excess of a predetermined amount to open said one of said contacts, said temperature responsive element thereupon effecting breaking of the cut-out circuit through the other of said contacts with a point intermediate the outer end of said heating element and the other wire of said circuit.

4. In a circuit cut-out of the character described, a core, an armature, a relay coil on said core, said armature being attracted by said core when said coil is energized with current in excess of a predetermined amount, a heat responsive element, a heating ,element therefor, said relay coil and said heating element being connected in series, a pair of contacts controlled by the position of said heat responsive element, a third contact connected between said relay coil and said heating element and coactable with one of said pair of contacts, a fourth contact connected with the free end of said heating element nections with the free ends of said heat responsive element and said relay coil.

5 In a circuit cut-out of the character decore, said armature being attracted by said core when said coil is energized with current in excess of a predetermined amount, a heat responsive element, a heating element therefor, said relay coil and said heating element being connected in series, a pair of contacts controlled by the position of said heat r spon ive element, a third contact connected between said relay coil and said heating element and coactable with one of said pair of contacts, a fourth contact connected with the free end of said heating element and coactable with the other of said pair of contacts, said third contact being normally engaged with said one of said pair of contacts, said fourth contact being normally separated from said other of said pair of contacts and engageable therewith by movement of said armature when attracted by said core, and said other of said pair of contacts being disengaged from said fourth contact when said bimetal element warps in response to heat from said heating element. 6. A circuit cut-out of the character described comprising an armature, a relay coil, said armature being moved by energization of said coil with current in excess of a predetermined amount, a heat responsive element, a heating element therefor, said relay coil and said heating element being connected in series, a pair of contacts controlled by the position of said heat responsive-element, a third contact connected between said relay coil and said heating element and coactable with one of said pair of contacts, a fourth contact connected with the free end of said heating element and coactable with the other of said pair of contacts, said third contact being normally engaged with said one of said pair of contacts, said fourth contact being normally separated from said other of said pair of contacts and engageable therewith by movement of said armature when attracted by said core, and supply circuit connections with the free ends of said relay coil and said heat responsive element, said element returning to initial position after a time period due to dissipation of heat therefrom after the circuit of said heating element is opened.

7. In a circuit cut-out, a core, anarmature, a relay coil on said core, said armature being attracted by said core when said coil is energized with current in excess of a predetermined amount, a bimetal element, a heating element therefor, said relay coil and said heating element being connected in series, a pair of contacts on said bimetai element, a third contact connected between said relay coil and said heating element and engageable with one of said pair of contacts, a fourth contact connected with the free end of said heating element and engageable with the other of said pair of contacts, said third contact being normally engaged with said one of said pair of contacts, said fourth contact being normally separated from said other of said pair of contacts and engageable therewith by movement of said armature when attracted by and an armature, said armature being responsive only when current through to and thereby moved said coil exceeds a predetermined amount, a

scribed, a core, an armature, a relay coil on said heating element, means movable in response to heat therefrom, a first circuit connection between said means and said relay coil including contacts, a second circuit connection between said means and said heating element including second contacts, said armature opening said first contacts and closing said second contacts to energize said heating element when said armature moves in response to current through said relay coil in excess of said predetermined amount, said means thereupon opening said second contacts and thereby the circuit through said relay and maintaining it open until said means cools sufficiently to return to closed circuit position.

9. In a circuit cut-out, the combination of a magnetic relay including a coil and an armature, and a thermal relay including a heating element and heat absorbing means movable in response to heat therefrom, a circuit connection including contacts between said heat absorbing means and said relay coil, a circuit connection between said heating element and heat absorbing means, the last circuit connection including contacts,

relay and a thermal relay including a heating said armature moving in response to current Y through said relay coil in excess of a predetermined amount and thereby opening said first contacts and closing said second contacts, said heating element being thereby heated and heating said heat absorbing means to thereby cause it to open the circuit through said relay by sepelement, he coil of said magnetic. relay and the heating element of said thermal relay being connected in series, a contact between said heating element and said coil, the temperature responsive element of said thermal relay being engageable therewith, one circuit connection with said coil and another circuit connection with said temperature responsive element, a second contact at the free end of said heating element and engageable with said temperature responsive element, said temperature responsive element normally engaging said firstcontact and being movable by said arjmature of said magnetic relay to efiect separation thereof from said first contact and close said second contact with relation to said temperature responsive element to effect current flow through said heating element, said temperature responsive element thereupon disengaging from said second contact and thereby efiecting breaking of the circuit through said relay coil and said heating element.

BURTON E. SHAW. 

